The temporal dynamics of biogeochemical variables derived from a coupled 3-D model of the Mediterranean Sea are evaluated for the last 50 years (1960–2010) against independent data on fisheries catch per unit effort (CPUE) for the same time period. Concordant patterns are found in the time series of all of the biological variables (from the model and from fisheries statistics), with low values at the beginning of the series, a later increase, with maximum levels reached at the end of the 1990s, and a posterior stabilization. Spectral analysis of the annual biological time series reveals coincident low-frequency signals in all of them. The first, more energetic signal peaks around the year 2000, while the second, less energetic signal peaks near 1982. Almost identical low-frequency signals are found in the nutrient loads of the rivers and in the integrated nutrient levels in the surface marine ecosystem. Nitrate concentration shows a maximum level in 1998, with a later stabilization to present-day values, coincident with the first low-frequency signal found in the biological series. Phosphate shows maximum concentrations around 1982 and a posterior sharp decline, in concordance with the second low-frequency signal observed in the biological series. That result seems to indicate that the control of marine productivity (plankton to fish) in the Mediterranean is principally mediated through bottom-up processes that could be traced back to the characteristics of riverine discharges. The high sensitivity of CPUE time series to environmental conditions might be another indicator of the overexploitation of this marine ecosystem. Key Points Biogeochemical evolution of the Mediterranean over the past 50 years River nutrient loads drive primary and secondary productions Strong link between low trophic levels and fisheries

中文翻译：

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近 50 年来地中海海洋生产力的生物地球化学控制

对过去 50 年（1960-2010 年）从地中海耦合 3-D 模型得出的生物地球化学变量的时间动态与同一时期的每单位努力渔获量 (CPUE) 的独立数据进行评估。在所有生物变量（来自模型和渔业统计数据）的时间序列中发现了一致的模式，序列开始时值较低，随后增加，在 1990 年代末达到最大值，并且后部稳定。年度生物时间序列的频谱分析揭示了所有这些中重合的低频信号。第一个能量较高的信号在 2000 年左右达到峰值，而第二个能量较低的信号在 1982 年附近达到峰值。在河流的养分负荷和表层海洋生态系统的综合养分水平中发现了几乎相同的低频信号。硝酸盐浓度在 1998 年达到最高水平，随后稳定到今天的值，与生物学系列中发现的第一个低频信号一致。磷酸盐在 1982 年左右显示出最大浓度，随后急剧下降，这与生物学系列中观察到的第二个低频信号一致。这一结果似乎表明，地中海对海洋生产力（浮游生物到鱼类）的控制主要是通过自下而上的过程来调节的，这可以追溯到河流排放的特征。CPUE 时间序列对环境条件的高度敏感性可能是该海洋生态系统过度开发的另一个指标。要点 过去 50 年地中海的生物地球化学演变 河流养分负荷推动初级和次级生产 低营养水平与渔业之间的密切联系